Erythema Multiforme: Acute immune-mediated reaction characterized by appearance of target-like lesions on skin often accompanied by bullae involving oral, genital, or ocular mucosa.

-Epidemiology: most common in young adults 20-40

-2 forms: Minor (only mild or no mucosal involvement) or major (severe mucosal involvement and may have systemic symptoms like fever and arthralgias)

-Triggers: 90% infectious (most commonly HSV, but can be viral, bacteria, or fungal)

-Cases have been associated with meds (most commonly NSAIDs), malignancy, autoimmune disease, vaccines, radiation, sarcoidosis, and even menstruation

-Treatment: Usually self-limited within a few weeks